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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

GBT20, a 20.48 Gbps PAM4 Optical Transmitter Module for Particle Physics Experiments

We present a pluggable radiation-tolerant 4-level Pulse-Amplitude-Modulation (PAM4) optical transmitter module called GBT20 (Giga-Bit Transmitter at 20 Gbps) for particle-physics experiments. GBT20 has an OSFP or firefly connector to input 16-bit data each at 1.28 Gbps. The GBT20 drives a VCSEL die with an LC lens or a VCSEL TOSA and interfaces an optical fiber with a standard LC connector. The minimum module, including the host connector, occupies 41 mm x 13 mm x 6 mm. At 20.48 Gbps, the minimum Transmitter Dispersion Eye Closure Quaternary (TDECQ) is around 0.7 dB. The power consumption is around 164 mW in the low-power mode. The SEE cross-section is below 7.5x10^(-14) cm^2. No significant performance degrades after a TID of 5.4 kGy.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Epoxy-based infrared filter assembly and associated fabrication devices and method

Epoxy-based inline infrared (IR) filter assembly, and manufacture and use of the same. Co-axial infrared filter assemblies comprise a substantially cylindrical filter body forming a central cavity characterized by opposing holes at each end. The filter body forms an outer conductor, and SMA connectors coupled to the opposing holes at each end of the body are electrically coupled to form an inner conductor positioned along a long axis of the filter body. An infrared absorbing material (such as castable epoxy resin) fills the central cavity of the filter body. Methods for producing the co-axial infrared filter include pressing SMA connectors into the respective ends of the filter body, electrically coupling the SMA connectors, and filling the filter body with epoxy. Electronic systems for operating a dark matter detector include a feedline comprising a coaxial filter configured to advantageously block infrared noise.

Spahn, Gabriel↗
DOE OSTI2012

Design of the Trigger Interface and Distribution Board for CEBAF 12 GeV Upgrade

The design of the Trigger Interface and Distribution (TID) board for the 12 GeV Upgrade at the Continuous Electron Beam Accelerator Facility (CEBAF) at TJNAL is described. The TID board distributes a low jitter system clock, synchronized trigger, and synchronized multi-purpose SYNC signal. The TID also initiates data acquisition for the crate. With the TID boards, a multi-crate system can be setup for experiment test and commissioning. The TID board can be selectively populated as a Trigger Interface (TI) board, or a Trigger Distribution (TD) board for the 12 GeV upgrade experiments. When the TID is populated as a TI, it can be located in the VXS crate and distribute the CLOCK/TRIGGER/SYNC through the VXS P0 connector; it can also be located in the standard VME64 crate, and distribute the CLOCK/TRIGGER/SYNC through the VME P2 connector or front panel. It initiates the data acquisition for the front crate where the TI is positioned in. When the TID is populated as a TD, it fans out the CLOCK/TRIGGER/SYNC from trigger supervisor to the front end crates through optical fibres. The TD monitors the trigger processing on the TIs, and gives feedback to the TS for trigger flow control. Field Programmable Gate Arrays (FPGA) is utilised on TID board to provide programmability. The TID boards were intensively tested on the bench, and various setups.

CEBAF upgrade↗
DOE OSTI2012

Design of the Trigger Interface and Distribution Board for CEBAF 12 GeV Upgrade

The design of the Trigger Interface and Distribution (TID) board for the 12 GeV Upgrade at the Continuous Electron Beam Accelerator Facility (CEBAF) at TJNAL is described. The TID board distributes a low jitter system clock, synchronized trigger, and synchronized multi-purpose SYNC signal. The TID also initiates data acquisition for the crate. With the TID boards, a multi-crate system can be setup for experiment test and commissioning. The TID board can be selectively populated as a Trigger Interface (TI) board, or a Trigger Distribution (TD) board for the 12 GeV upgrade experiments. When the TID is populated as a TI, it can be located in the VXS crate and distribute the CLOCK/TRIGGER/SYNC through the VXS P0 connector; it can also be located in the standard VME64 crate, and distribute the CLOCK/TRIGGER/SYNC through the VME P2 connector or front panel. It initiates the data acquisition for the front crate where the TI is positioned in. When the TID is populated as a TD, it fans out the CLOCK/TRIGGER/SYNC from trigger supervisor to the front end crates through optical fibres. The TD monitors the trigger processing on the TIs, and gives feedback to the TS for trigger flow control. Field Programmable Gate Arrays (FPGA) is utilised on TID board to provide programmability. The TID boards were intensively tested on the bench, and various setups.

CEBAF upgrade↗
DOE OSTI2012

A structural model of anti-anti-[sigma] inhibition by a two-component receiver domain: the PhyR stress response regulator

PhyR is a hybrid stress regulator conserved in {alpha}-proteobacteria that contains an N-terminal {sigma}-like (SL) domain and a C-terminal receiver domain. Phosphorylation of the receiver domain is known to promote binding of the SL domain to an anti-{sigma} factor. PhyR thus functions as an anti-anti-{sigma} factor in its phosphorylated state. We present genetic evidence that Caulobacter crescentus PhyR is a phosphorylation-dependent stress regulator that functions in the same pathway as {sigma}{sup T} and its anti-{sigma} factor, NepR. Additionally, we report the X-ray crystal structure of PhyR at 1.25 {angstrom} resolution, which provides insight into the mechanism of anti-anti-{sigma} regulation. Direct intramolecular contact between the PhyR receiver and SL domains spans regions {sigma}{sub 2} and {sigma}{sub 4}, likely serving to stabilize the SL domain in a closed conformation. The molecular surface of the receiver domain contacting the SL domain is the structural equivalent of {alpha}4-{beta}5-{alpha}5, which is known to undergo dynamic conformational change upon phosphorylation in a diverse range of receiver proteins. We propose a structural model of PhyR regulation in which receiver phosphorylation destabilizes the intramolecular interaction between SL and receiver domains, thereby permitting regions {sigma}{sub 2} and {sigma}{sub 4} in the SL domain to open about a flexible connector loop and bind anti-{sigma} factor.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Investigation into the Development and Testing of a Simplex Capacitance Sensor for Rotor Tip Clearance Measurement in Turbo Machinery

The rotor tip clearance is a vital parameter to characterize turbomachinery performance. It is an essential measurement during engine development and testing. The efficiency of the major modules like fan, compressor and turbine depends on the optimum running clearances. The capacitive sensor is preferred for tip clearance measurements because of various inherent advantages. They are fabricated through complex processes for turbomachinery application and are expensive. These sensors are exposed to harsh engine environments and are likely to exhibit degraded performance. Insulation failure at sensing head, connector contamination and micro-cracks in the MI (Mineral Insulated) cable leads to noise in the signal output. Frequent mechanical failures are also seen due to work hardening of MI cables, lead connector detachments and failure of micro fins at interconnects. Fault fixing of these is tedious and very expensive. This paper presents the concerted effort in developing a simple capacitance sensor addressing potential sensor failure issues. The design features include simple construction, ease of sensor assembly, component realization and troubleshooting. The design also addresses all safety requirements. The sensor has a large sensing area (7.6 mm diameter) producing very stable, high-level signal. The developed sensor produces output that varies from 1 V{sub P-P} to 11 V{sub P-P} for blade-tip gaps between 3 mm to 0.4 mm respectively. Blade pass simulation studies across the sensor, display almost flat response at minimum clearance. This feature results in very minimal data acquisition errors. The sensor along with RC (Resistance-Capacitance) conditioning electronics was successfully used for clearance measurement on fan stage of gas turbine engine. Test results are in line with the predictions. Extensive tip clearance measurements on the engine validate the design. The current work provides an insight into the development of a simplex capacitance sensor for tip clearance measurement.

42 ENGINEERING↗
DOE OSTI2019

Contact Load in a Tight Thermomechanical Pipeline Joint

The contact problem for pipeline connection by means of a connector with shape memory is solved. In the solution, the actual deformation of the pipe is taken into account on the basis of the thermomechanical diagram. The thermal shape recovery of the connector is modeled. The conditions in which this approach may be employed are formulated. As an example, the contact load in a joint is determined.

42 ENGINEERING↗
DOE OSTI2026

Thermal Evaluation of CCS and NACS Reference Devices and Adapters

A review of NLR's work in charging system reliability for charging inlets, connectors, and adapters. The review includes a detailed discussion on (a) the development of a reference device for the thermal performance of charging connectors and adapters, (b) evaluation of charging adapters and their thermal warning and shutdown response, (c) implications of side-load from real-world implementations, and (d) strengthening the conformance evaluation for end caps based on field data.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS2020

Testing

Testing is conducted to verify that the connectors will properly perform over time (reliability) per the application requirements. Testing by the manufacturer usually involves performance testing per the datasheet requirements. However, the customer may have applications that require performance under unique operational and environmental conditions. In general, electrical tests for connectors include dielectric withstanding voltage, low-signal-level contact resistance, insulation resistance, contact resistance, and standing wave ratio. Environmental tests include humidity, temperature, and contaminating conditions, as well as mechanical stress environments including vibration, mechanical shock, and durability cycling exposures.

Connectors, testing, Dielectric Withstanding Volta↗
DOE OSTI2020

Interfacing HDF5 with a scalable object‐centric storage system on hierarchical storage

Summary Object storage technologies that take advantage of multitier storage on HPC systems are emerging. However, to use these technologies at present, applications have to be modified significantly from current I/O libraries. HDF5, a widely used I/O middleware on HPC systems, provides a virtual object layer (VOL) that allows applications to connect to different storage mechanisms transparently without requiring significant code modifications. We recently designed the proactive data containers (PDC) object‐centric storage system that provides the capabilities of transparent, asynchronous, and autonomous data movement taking advantage of multiple storage tiers—a decision that has so far been left upon the user on most current systems. To enable PDC's features through HDF5 without modifying application codes, we have developed an HDF5 VOL connector that interfaces with PDC. We present in this article the connector interface and evaluate its performance on Cori, a Cray XC40 supercomputer located at the National Energy Research Scientific Computing Center (NERSC). Our evaluation demonstrates up to an 8× improvement compared with HDF5 that has the most recent optimizations.

Mu, Jingqing↗
DOE OSTI2019

Influence of Wear Test Parameters on the Electrical Contact Performance of Brass Alloy/Copper Contactors Under Fretting Wear

Fretting of mated electronic connectors may be due to extreme increase in contact resistance. We present a detailed analysis of contact resistance by fretting experiments using brass alloys/copper contact pairs. The relationship between wear mechanisms and contact resistance was determined. The influence of fundamental factors such as normal load, displacement amplitude, and current on contact resistance change was also evaluated. It was found out that displacement amplitude, normal load, and current are important parameters for infinite lifetime or stable electrical resistance during fretting condition. Influence of displacement amplitude on the electrical contact performance might be affected by wear debris in the contact area. Electric contact performance could be improved by increasing the power current, which could break down the thick oxide film formed. The predicted working lifetime and reliability requirements of the connector were determined to optimize and extend the service life under the working condition.

36 MATERIALS SCIENCE↗
DOE OSTI2016

High voltage testing for the Majorana Demonstrator

The Majorana Collaboration is constructing theMajorana Demonstrator, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in 76Ge. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of theMajorana Demonstrator. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of the high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the Majorana Demonstrator was characterized and the micro-discharge effects during theMajorana Demonstrator commissioning phase were studied. A stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge.

high-voltage↗
DOE OSTI2024

Quick-connect scanning tunneling microscope head with nested piezoelectric coarse walkers

To meet changing research demands, new scanning tunneling microscope (STM) features must constantly evolve. We describe the design, development, and performance of a modular plug-in STM, which is compact and stable. The STM head is equipped with a quick-connect socket that is matched to a universal connector plug, enabling it to be transferred between systems. This head can be introduced into a vacuum system via a load-lock and transferred to various sites equipped with the connector plug, permitting multi-site STM operation. Its design allows for reliable operation in a variety of experimental conditions, including a broad temperature range, ultra-high vacuum, high magnetic fields, and closed-cycle pulse-tube cooling. The STM’s compact size is achieved by a novel nested piezoelectric coarse walker design, which allows for large orthogonal travel in the X, Y, and Z directions, ideal for studying both bulk and thin film samples ranging in size from mm to μm. Its stability and noise tolerance are demonstrated by achieving atomic resolution under ambient conditions on a laboratory desktop with no vibrational or acoustic isolation. The operation of the nested coarse walkers is demonstrated by successful navigation to a μm-sized 2D sample.

Instruments & Instrumentation↗
DOE OSTI2016

A small protein inhibits proliferating cell nuclear antigen by breaking the DNA clamp

Proliferating cell nuclear antigen (PCNA) forms a trimeric ring that encircles duplex DNA and acts as an anchor for a number of proteins involved in DNA metabolic processes. PCNA has two structurally similar domains (I and II) linked by a long loop (inter-domain connector loop, IDCL) on the outside of each monomer of the trimeric structure that makes up the DNA clamp. All proteins that bind to PCNA do so via a PCNA-interacting peptide (PIP) motif that binds near the IDCL. A small protein, called TIP, binds to PCNA and inhibits PCNA-dependent activities although it does not contain a canonical PIP motif. The X-ray crystal structure of TIP bound to PCNA reveals that TIP binds to the canonical PIP interaction site, but also extends beyond it through a helix that relocates the IDCL. TIP alters the relationship between domains I and II within the PCNA monomer such that the trimeric ring structure is broken, while the individual domains largely retain their native structure. Small angle X-ray scattering (SAXS) confirms the disruption of the PCNA trimer upon addition of the TIP protein in solution and together with the X-ray crystal data, provides a structural basis for the mechanism of PCNA inhibition by TIP.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Rice Cellulose SynthaseA8 Plant-Conserved Region Is a Coiled-Coil at the Catalytic Core Entrance

The crystallographic structure of a rice (Oryza sativa) cellulose synthase, OsCesA8, plant-conserved region (P-CR), one of two unique domains in the catalytic domain of plant CesAs, was solved to 2.4 Å resolution. Two antiparallel α-helices form a coiled-coil domain linked by a large extended connector loop containing a conserved trio of aromatic residues. The P-CR structure was fit into a molecular envelope for the P-CR domain derived from small-angle X-ray scattering data. The P-CR structure and molecular envelope, combined with a homology-based chain trace of the CesA8 catalytic core, were modeled into a previously determined CesA8 small-angle X-ray scattering molecular envelope to produce a detailed topological model of the CesA8 catalytic domain. The predicted position for the P-CR domain from the molecular docking models places the P-CR connector loop into a hydrophobic pocket of the catalytic core, with the coiled-coil aligned near the entrance of the substrate UDP-glucose into the active site. In this configuration, the P-CR coiled-coil alone is unlikely to regulate substrate access to the active site, but it could interact with other domains of CesA, accessory proteins, or other CesA catalytic domains to control substrate delivery.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Inverted Geometry Ceramic Insulators in High Voltage DC Electron Guns for Accelerators

A direct current (dc) high voltage photo-emission electron gun operating at 130 kV is utilized at the Jefferson Lab (JLab) Continuous Electron Beam Accelerator Facility to generate spin-polarized electrons for nuclear physics experiments. Over the past decade, JLab has tested and implemented inverted-geometry ceramic insulators in photoguns, connecting the cathode electrode in vacuum to the high voltage power supply using commercial high voltage cables. This contribution reports on tests performed up to 375 kV dc, implementation of inverted insulators in a 300 kV dc photogun generating magnetized electron beams, and describes plans to develop a reliable insulator-cable connector for applying 500 kV dc to a future polarized beam photogun operating reliably and without field emission at 350 kV.

Hernandez-Garcia, C.↗
DOE OSTI2015

SU-E-T-66: A Prototype for Couch Based Real-Time Dosimetry in External Beam Radiotherapy

Purpose: The main purpose of this study is to design a prototype for couch-based based real time dosimetry system in external beam radiotherapy Methods: A prototype of 100 ionization chambers was designed on a printed circuit board by etching the copper layer and each ionization chamber was wired to a 50 pin connector. The signals from the two 50 pin connectors collected from the ionization chambers were then transferred to a PXI module from National Instruments. The PXI module houses a current amplifier that amplifies the charge collected from the ionization chamber. The amplified signal is then sent to a digital multimeter module for converting the analog signal to digital signal. A software was designed in labview to read and display the signals obtained from the PXI module. A couch attachment frame was designed to house the 100 ionization chamber module. The frame was fixed underneath the treatment couch for measuring the dose during treatment. Resutls: The ionization chamber based prototype dosimetry was tested for simple radiotherapy treatment fields and found to be a useful device for measuring real time dosimetry at the treatment couch plane. This information could be used to assess the delivered dose to a patient during radiotherapy. It could be used as an invivo dosimeter during radiotherapy. Conclusion: In this study, a prototype for couch based real time dosimetry system was designed and tested. The prototype forms a basis for the development of large scale couch based real time dosimetry system that could be used to perform morning QA prior to treatment, assess real time doses delivered to patient and as a device to monitor the output of the treatment beam. Peter MacCallum Cancer Foundation.

60 APPLIED LIFE SCIENCES↗